Resonant acoustical article of manufacture



Patented Mar. 13, 1934 PATENT OFFICE.

RESONANT ACOUSTICAL ARTICLE OF MANUFACTURE Waldo G. Morse, Yonkers, N.Y.

No Drawing. Application November 20, 1930, Serial No. 497,055

10 Claims.

My invention relates to an article of manu facture or composition ofmatter useful in structures designed for or employed in the production,re-production, amplification, modification or perpetuation of sound,tones, tonal qualities or vibrations causing, produced by oraccompanying the same and for various other uses, and the process ofmaking the same. It has for its objects the production of such materialor article of manufacture, and its employment in the structures namedand in various structures where resonance or tone control is desired.

A further object is the production of articles useful for variouspurposes made from or out 1 of said article of manufacture, usefulbecause of their lightness, durability, strength, ease of handling andadaptability to varying requirements as to character and appearance.

In the past problems of resonance have been treated as the result ofmass vibration. As distinguished from that I have observed thatproperties of resonance are to a large degree dependent on molecularmotion within the body of the material in conjunction with orindependent of mass motion; in other words, the elastic reactions of amultitude of minute elements under tension.

I have also observed that structures comprising minute spherical orrounded particles are more likely to be highly and pleasantly resonantthan angular or abrazed materials. It has been noted for example in oldviolins, famous for their tone, that as seen under the microscope thewood seems to have worked itself into somewhat rounded particles.

A long series of experiments along these theoretical lines have led meto devise a resonant material consisting in general of minute, hardrounded particles as the primary ingredient, With an elastic bindermodified by the addition of fine flakes or splinters of fibrous materialto soften the resonance to any degree desired. The molecular tensions inthe ingredients and the myriad of stresses or tensions caused by thehardening or shrinking of the binder material produce unusualresonanting qualities. In any case, whatever the theoretical cause, thematerials so produced have been found to give excellent results in alarge number of experimental structures.

In carrying out my invention I preferably use marl to supply the minutespherical or rounded particles, oat hulls for the resilient or fibrousmaterial, and rubber or glue for the binder.

The binder may be the common flake or ground glue of any desiredquality, white French cabinet glue, casein glue, blood or albumen glue,or any other variety of glue capable of hardening sufiicicntly and whichcontracts upon cooling and drying or either, or rubber hardened orvulcanized by any well known means.

The marl is of the type found in nature precipitated from solution inthe waters of lakes and ponds. Such marl is precipitated carbonate oflime and consists of detached minute or microscopic globes or spheres.It is preferably reduced from its plastic moist form as found in natureand caked and dried and then abraided to the form of a powder composedof its ultimate globular molecules or particles as precipitated, havingthe same free and unattached one from the other, all shells and otherextraneous substances having been first sifted out. Where the marl issuiiiciently free from admixture or is mixed chiefly with a proportionof fine clay as sometimes is the case, it is practicable to use thematerial without drying or grinding. Such marl is composed of globularparticles of microscopic size and is to be distinguished from materialscomposed of angular, irregular, prismatic or abraded structures. Mostmineral or earthy substances, as Well as materials made from sea shells,such as chalk, for example, have a crystalline or angular structure.Materials commonly employed as fillers in the making of compositematerials, such as sands, whiting, infusorial earth, ground rottenstone, lime-stone and the like are produced by the abrasion of massivematerials or the grinding of hard solid substances. On the contrary,marl as employed by me is composed of free and uncemented sphericalparticles and may be softened and put into a plastic form or suspensionby the use of water and without any grinding, therefore being differentfrom baked clay or pottery. Other spherical or oval particles ofmicroscopic or minute size and of requisite hardness are within thescope of my invention whether of animal origin as is the case with marl,or of vegetable origin as in the case of minute spores or seeds whichalso I employ.

The oat hulls to be employed preferably, are ground or broken uplongitudinally into slivers of appreciable length and accordingly takethe form of stifi pointed splinters or particles slightly curved orbowed and slightly concaveconvex and having the characteristic siliciouscoating upon the convex or outer sides of the hulls with the materialgrowing softer and more fibrous as the cellulose structure of the hullgrows more and more predominant toward its inner surface.

All meal, starch, gluten and the like which are found in the kernels ofoats should be separated out or are eliminated and discarded before use.It is possible to use the hulls in their original form, as they arediscarded in the production of meal, and without re-grinding. The hullsof wheat, rye, barley, corn, rice or other grains, may be usedseparately or blended with oat hulls or each other in structures ofvarying sizes or forms to secure diverse effects, though I prefer thoseof oats. Also splinters of bamboo, ivory, bone, nut shells, wood or thelike comparable in size and shape to grain hulls may be used; such othermaterials needing not of necessity to be pointed or concavo-convex toproduce their several characteristic results. The structure of corn cobsor similar material is entirely different from that of oat hulls or thehulls of other grains and from splinters as above described and groundcorn cobs would be useless for the purposes indicated in thisspecification. Wheat and other bran likewise is too fine to accomplishthe desired results and wholly unsuited to the purposes sought. Brancomes from an inner coating surrounding the kernel of grain and isdistinct from the hull. The reason for employing oat hulls or otherstiff, tough and resilient material is that slivers of such materialfurnish supports to the binding material, of such nature, that strainsor tensions resulting from the contraction of the binder put both thebinder and such hulls or like material under stress. The oat hulls andother specified materials are still and vibrant and in that respectserve a different purpose and perform a different function from anyserved or performed through the employment of a material such as flockor cotton or other soft absorbent or yielding material. The employmentof such material as grain hulls and the like above described inconjunction with a binder as distinguished from a material which simplyforms an inert filler constitute one phase of means employed in carryingout my invention. 7

Any stiff, fibrous or amorphous material in appreciable lengths, of sizein proper relation to the size of the particles of marl or the like, andresilience of proper co-efiicient to the strain and contraction andtensile strength of the binder and sufficient to produce desiredmolecular tension in the mass and to which the cement or binder to beemployed will adhere, may be used. Binders other than glue or rubber maybe used, but it is essential that the binder and the fixed materialemployed be such as are in proper relation of size, strength and natureand take or adhere together as do marl, oat hulls and glue, and do notcrack apart. The particular types described as preferred are foundadapted to phonograph and radio reproducers and diaphragms and toviolins.

The glue rubber or other similar binder is used in amounts exceedingthose required to produce cardboard, papier-mtch and the like. In myconstruction, the binding material is so in excess, as compared withcardboard or papiermach, that as it cools or dries and contracts underatmospheric or mechanical pressure as the case may be, the whole masswill solidify without the forming of dominant air spaces or loosecontacts and so will produce a resonant structure under internaltension, stress or strain by reason of the contraction of the bindingmaterial around and between the particles or pieces of materialcontained therein and surrounded thereby. All of the glues and othermaterials specified are known to shrink or contract in setting and soare adapted to produce the requisite strain or molecular tension in thesolidified mass. Glues, rubbers, gums and resins possess this feature inmarked degree.

In carrying out my invention employing the preferred forms of availablematerials as above set forth for the purposes primarily in view, that isto say, the production of a composite resonant substance under molecularinternal stress or tension, the procedure is as follows:

Common glue is hydrated and dissolved in the usual manner. Marl abradedinto a powder or softened into a paste by the addition of water is thenadded and thoroughly stirred into a un'form mixture, the entire massbeing kept hot. Proportions varying from one of glue to one of marl andup to six or more of marl, dry measure, have been found available forthe production of different types of the material and varying results.

Into the hot mass so formed and hydrated to about the consistency ofcream, are then stirred dry re-ground or comminuted oat hulls varyingfrom a small quantity say one-half in bulk that of the combined glue andmarl to a quantity several times such bulk, according to the characterof the product sought to be formed.

The material so compounded is spread upon forms or placed in molds orpressed into shape in any well known manner, and allowed to set, cooland harden, being thereafter removed for finishing and use.

It may be applied by means of a brush or knife or the like and allowedto harden under atmospheric pressure and one or more coats may be soapplied, or it may be formed in molds or otherwise shaped.

When compounded the material may be reserved for use and softened bymoisture and heat or may be broken up for dry pressing or forming as andwhen desired.

The nature and behavior of the materials during manufacture andhardening is such that the particles of marl remain rigid while the glueor rubber contracts greatly upon cooling, drying or setting. By suchcontraction the entire mass is put under great molecular strain ortension and a very tough, refractory, resilient and resonant productresults. When the proportion of marl is small, the binder is predominantin the mixture. When larger proportions of marl are employed, theproduct becomes horny but remains massive, while the addition of stilllarger proportions of marl causes the material to set with smallinterstices or air spaces throughout the mass.

Such characteristic results occur and persist as to the drying binderabout the particles of marl or other described equivalent in thematerial as combined with oat hulls or independently thereof, and aredescribed separately for that reason.

By such means, I have formed blocks and sheets of material and havefabricated phonograph amplifiers, horns, tone arms, sound boxes anddiaphragms and also radio horns all of the same in various sizes, shapesand of different di- Ill mensions and have made violins and otherthings.

. desirable tone. roidal, oval or rounded grains or particles are I havelearned that the resulting product and the characteristic resonance ofthe material and the tone quality obtained through its use may be variedwithin wide limits through variations in the quality of the binderemployed and the proportions of binder and marl used and also thatfurther and other modifications of the character of the material orarticle produced and the resonance of the same may be secured throughthe employment of smaller or larger proportions of oat hulls orvariations within certain limits in the size to which they arecomminuted.

By using glue and marl hydrated, barely sufliciently to maintainfluidity when heated to the boiling point, and using a larger quantityof glue and marl in proportion to the quantity of hulls, a very hardcomposition may be produced characterized by a high pitch and greatresonance when intonated, while by using a thinner glue or onecontaining a larger proportion of water, the product obtained whencooled and dried may show small interstices between the hulls or othermaterial with a lower characteristic resonance.

Generally speaking the mixture of glue and marl set under atmosphericpressure attains its greatest refractory point when the dried andhardened glue is just suilicient to fill completely 80' the intersticesamong the particles of marl, say one of glue and two of marl, dry weightstrength and high tonal pitch declines from that point as marl is added.When mechanical pressure is employed, smaller proportions of glue orother binder should be used. Like eiiects result from similar employmentof rubber.

With a proper admixture of glue or rubber and marl, the preferredquantity of oat hulls or their said equivalents to secure such maximum40' termination according to the sizes of the grains 45 of marl or otherspherical or rounded element and the pieces of the cat hulls or otherlike substance or substances and the pressure applied during setting.

The essential characteristic of marl which renders it available for theuses described is the rounded or globular shape of its particles. Suchcharacteristic as specified above is exceedingly advantageous insecuring resonance and Other masses of spherical sphecapable ofproducing similar results and various types of tone or timbre, when thegrains are of suitable small or microscopic size and adapted to coactwith the slivered or like material formed into the mass as for exampleprecipitates generally, minute seeds or grains, spores, pollen and othervegetable products natural or artificially produced single or combinedand of suitable size and physical characteristics.

The characteristic tone of the completed article when vibrating, tendsto be lowered and softened as the proportion of oat hulls or the like isincreased and the tendency to a continuation of any resonant movementinduced in the acteristics are of the greatest value, in sound producingor recording or re-producing instruments or devices.

In practice, l have stained and varnished articles produced, for thepurposes of preservation and decoration, and any results desired may beobtained by such methods.

indicated, any type of glue may be employed and any temper oi the sameor of gelatine glue, may be used.

I have produced similar results by the use of gum shellack, gum copal,gum and other gums, and resins, alone or in combination, having renderedthe same plastic by heat, and mixed them with marl and the like and oathulls and the like while hot and then allowed the mixture to cool.

Likewise I have produced most excellent resuits through the employmentof rubber as a binder, the marl and oat hulls and their equivalent beingmixed into the rubber while plastic or in the course of the productionof vulcanized or hard rubber by usual methods and then the massvulcanized by application of heat. An alternative method is to mix themarl and cat hulls or their equivalent with latex and then vulcanize themixture by use of well known means. Also it is apparent that for certaintypes of vibration and resonance soft rubber is preferable. Anyavailable commercial binder or composition be used in place of the gluegum or rubber, but the rubber is highly durable and resistant to heatand moisture. The material resulting from the use of heated gums or thelike must be shaped or molded, as it cannot be applied with a brush, butthese may be softened by a solvent where available, into an enamel orvarnish and then spread either cold or further softened by heat, anyexcess of solvent being driven off thereafter if need be, by reheating.Also any commercial product or Japan may be substitute for shellack.

By cooling the material under pressure, a smaller proportion of binderand larger proportion of marl or the like and hulls or the like may beused in producing a dense material or limiting the air spaces, thepressure hold ng the marl or the like and oat hulls or their equivalentin closer relation so that a smaller quantity of glue or binder willproduce a substantially dense mass when cooled and dried or hardened.

The resonant properties of the composition are due to the contraction ofthe glue or the like upon hardening which puts the whole mass of thematerial when hardened in a state of molecular tension, stress orstrain, such as is always conducive to resonance in any material, whilethe stiffness or rigidity of the hulls or the like adds to the resonanceand counteracts any tendency to warping.

It has become evident that variation in the timbre of a resonant body,such as I have described, may be secured by means of successive coatingsvarying in composition from clear glue or rubber or the like gradingthrough various degrees to a mixture carrying preponderant quantities ofsuch inert material, the same to be coated or brushed on to articlespreviously made from the material herein described, all in anypro-determined or desired manner.

Such additional coatings may be placed upon one or both sides of anarticle manufactured from the material specified, and successive layersmay be added of varying composition and resonant qualities as may bedesired or found in practice to yield the best tonal results for theparticular purposes desired, all in any predetermined or desired manner.Also, a base of thin wood, veneer or other suitable material may beused, whereon to build up the desired coatings.

In compounding my material the elements are mixed so that they areintimately and uniformly distributed together throughout the entire massand in practice it is possible to attain approximate uniformity ofmixture. For various uses, however, it is desirable that various layersor strata of the mass should contain a greater or less proportion of oneor the other of the ingredients, for example, greater proportions of oathulls or other like material may be used in a middle layer of a sheet tobe formed While greater proportions of glue or other binder and of marlor the like are employed in the mixture on either side. Or one side of asheet may be made to vary from the other, or one section oi a sheet orportion of a block may be made to vary from another or various parts maybe made to difier among themselves as desired for the accomplishment ofvarious useful purposes of tonal quality Within the charac-.

teristics of the material described.

In accordance with the provisions of the patent statutes I havedescribed the principle of my invention together with the material orapparatus which I now consider to represent the best embodiment thereof,but I desire it understood that my invention is not confined to theparticular material or processes herein shown and described, the samebeing merely illustrative, and that the invention can be carried out inother ways without departing from the spirit of my invention, andtherefore, I claim broadly the right to employ all equivalentcompositions coming within the scope of the appended claims.

The present application is a continuation in part of Serial Number168,230 filed February 14, 1927.

Having now described my invention, what I claim and desire to secure byLetters Patent 1. A highly resonant acoustical article of manufacturecomprising minute rounded particles, slivers of resilient particles, anda binder which contrasts in setting, adhering to and occupying the spacebetween said particles.

2. A highly resonant acoustical article of manufacture comprising minuterounded particles, slivers of resilient organic particles, and anelastic binder therebetween adhering thereto.

3. A highly resonant acoustical article of manufacture comprising marl,slivers of organic resilient particles, and a binder capable of adheringthereto.

4. A highly resonant acoustical article of manufacture comprising marl,comminuted resilient particles, and a binder which contracts in settingadhering thereto.

5. A highly resonant acoustical article of manufacture comprising marl,comminuted oat hulls, and a binder which contracts in setting, adheringthereto.

:3. A highly resonant acoustical article of manufacture comprising marl,slivers of resilient organic material, and a resilient binder.

'7. A highly resonant acoustical article of manufacture comprising marl,comminuted oat hulls, and an elastic binder which contracts in setting.

8. A highly resonant acoustical article of manufacture comprising minuterounded particles of precipitated calcium carbonate, slivers ofresilient organic material, and a binder adhering thereto whichcontracts in setting, substantially as shown and described.

9. A highly resonant acoustical article of manufacture comprising marl,comminuted oat hulls, and a binder adhering thereto.

10. A highly resonant acoustical article of manufacture comprising marl,comminuted grain hulls, and a resilient binder adhering thereto.

WALDO G. MORSE.

